City water report · 2026

Is Chicago Tap Water Safe to Drink?

Short answer: In the 2024–2026 records we hold for Chicago, no listed result is above a legal limit. Also worth knowing: the water is hard. 4 substances were detected and 30 were tested and not detected. The water is from Chicago Department of Water Management, serving 2,721,308 residents.

  • Year 2026
  • Utility Chicago Department of Water Management
  • Coverage 34 records
  • Updated 2026-10-15
Water utility

Where Chicago’s water comes from

Utility
Chicago Department of Water Management
Water system
CHICAGO · IL0316000
Source water
Surface water
Disinfectant
Chlorine
Population served
2,721,308
Reporting period
Sampled 2024–2026
Monitoring coverage
34 records · 4 of 4 groups measured
Service lines
350,531 lead, 10,326 galvanized, 39,427 unknown material (EPA inventory, 2026Q2)
Likely match, check your bill

Your water bill or annual water quality report names your actual supplier.

  • CHICAGOThis report
    IL0316000 · 2,721,308 served
Why this matters
  1. 1
    Source

    Surface water

  2. 2
    Treatment

    Treated and disinfected with chlorine.

  3. 3
    Distribution

    Mains, then your building’s service line.

  4. 4
    Your tap

    Plumbing inside the building is outside this record.

At a glance

Chicago water in four numbers

Purity ScoreCHICAGO · PWSID IL0316000
4Detected1 above a reference
1Above a referenceof 34 records
0Health-based violationslast 10 years · EPA SDWIS

No measured result is above a legal limit; the water is hard.

What we found

4 detected results, by distance from their limit

Lead (90th percentile)Within reference · Action level15 µg/L federal action level6.4µg/L
① · Measured

6.4 µg/L, sampled 2026–2026 monitoring period (still open). EPA SDWIS (Lead & Copper Rule).

② · Compared

15 µg/L federal action level. EPA health goal (MCLG): 0.

③ · Meaning

The 90th-percentile tap result was 6.4 µg/L (below the 15 µg/L action level).

④ · Where it matters

Usually from lead service lines, solder and fixtures inside buildings, after the water leaves treatment.

⑤ · What to do

Test your own tap first. To reduce it: Lead-certified carbon filter, or reverse osmosis (NSF/ANSI 53 (lead)).

See the evidence record →
Total trihalomethanes (TTHM)Within reference · Federal MCL80 ppb federal MCL26.4ppb
① · Measured

26.4 ppb, sampled 2025. Utility CCR.

② · Compared

80 ppb federal MCL: a legal limit.

③ · Meaning

26.4 ppb (below the 80 ppb federal limit).

④ · Where it matters

Forms in the pipes as the disinfectant reacts with natural organic matter.

⑤ · What to do

Test your own tap first. Technologies that can reduce it: Activated carbon, Reverse osmosis.

See the evidence record →
Haloacetic acids (HAA5)Within reference · Federal MCL60 ppb federal MCL13.8ppb
① · Measured

13.8 ppb, sampled 2025. Utility CCR.

② · Compared

60 ppb federal MCL: a legal limit.

③ · Meaning

13.8 ppb (below the 60 ppb federal limit).

④ · Where it matters

Forms in the pipes as the disinfectant reacts with natural organic matter.

⑤ · What to do

Test your own tap first. Technologies that can reduce it: Activated carbon, Reverse osmosis.

See the evidence record →
Water hardnessAbove aesthetic · Aesthetic, no health limitAesthetic, no federal health limit8.2gpg
① · Measured

8.2 gpg, sampled 2025. Utility CCR.

② · Compared

Aesthetic, no federal health limit.

③ · Meaning

140 mg/L as CaCO3 (8.2 grains/gal), hard. Aesthetic (scale/appliances), not a health finding.

④ · Where it matters

Shows up as scale in kettles, water heaters and fixtures.

⑤ · What to do

Test your own tap first. To reduce it: Ion-exchange water softener (NSF/ANSI 44 (softeners)).

See the evidence record →
30 others tested, none detectedshow
  • 11Cl-PF3OUdS
  • 8:2 FTS
  • 4:2 FTS
  • 6:2 FTS
  • ADONA
  • 9Cl-PF3ONS
  • HFPO-DA (GenX)
  • Lithium
  • NEtFOSAA
  • NMeFOSAA
  • NFDHA
  • PFEESA
  • PFMPA
  • PFMBA
  • PFBS
  • PFBA
  • PFDA
  • PFDoA
  • PFHpS
  • PFHpA
  • PFHxS
  • PFHxA
  • PFNA
  • PFOS
  • PFOA
  • PFPeS
  • PFPeA
  • PFTA
  • PFTrDA
  • PFUnA

CHICAGO (EPA PWSID IL0316000) delivers surface water to 2,721,308 residents. This report reflects 29 individual PFAS result(s) from the source UCMR5 observations and the latest Lead & Copper Rule 90th-percentile result. The utility's 2025 CCR reports hard water and chlorine disinfection.

Track record

0health-based violations in the last 10 years

From EPA SDWIS. A clean violation history means no enforcement action was recorded; it does not cover contaminants without a limit.

Your household

Your tap can differ from the city record

The record describes water leaving treatment and samples across the system. Pipes, solder and fixtures inside a building can add lead the record can’t see, especially in older buildings with lead service lines.

Test your water
  1. City
    Treated water

    Measured in this report

  2. Mains
    Distribution network

    Sampled across the system

  3. Building
    Service line and plumbing

    Not in this record

  4. Tap
    Your glass

    Only a tap test measures it

Test first, then treat

Three steps from a record to your glass

  1. 01Test

    Know what comes from your tap, starting with a first-draw lead sample.

  2. 02Match

    Compare each result with its named reference in our test reader.

  3. 03Treat

    Choose a technology certified for what your test found.

Commercial

Test kits

Affiliate links

Screening tells you if something is worth a closer look; a lab result is the number you can act on.

As an Amazon Associate, PurityMap earns from qualifying purchases. Affiliate disclosure.

  • Lab-certified results

    ETR Labs Basic Water Quality Test Kit

    ETR Laboratories

    50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria

    What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.

  • Screening: quick check, not lab-grade

    Varify 17-in-1 Complete Water Test Kit

    Varify

    17 strip readings, including lead, chlorine, fluoride, iron and hardness, plus 2 coliform bacteria tests

    • Turnaround: About 1 minute; the bacteria test takes 48 hours

    What it can't tell you: Strip colors give rough ranges, not lab numbers, and it cannot detect PFAS or arsenic.

When your results arrive, read them here → · Compare every kit we list

Treatment matching

What can reduce what was found here

FindingReference typeTechnologyCertification to check
Lead (90th percentile)6.4 µg/LAction levelLead-certified carbon filter, or reverse osmosisNSF/ANSI 53 (lead)
Total trihalomethanes (TTHM)26.4 ppbFederal MCLActivated carbon, Reverse osmosisCheck the certifier’s listing
Haloacetic acids (HAA5)13.8 ppbFederal MCLActivated carbon, Reverse osmosisCheck the certifier’s listing
Water hardness8.2 gpgAesthetic, no health limitIon-exchange water softenerNSF/ANSI 44 (softeners)

Understand water treatment technologies →

Commercial

Filters for the lead found in Chicago water

Affiliate links

★ Best choice: Brita Elite Water Filter Pitcher, certified for lead.

Filters for the lead found in Chicago water
PickProductDetails and priceCertificationWhy it’s listedLink
★ Best choicePitcherBrita Elite Water Filter PitcherBritaTreatsleadPrice$Certified for Lead (NSF/ANSI 53, WQA)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodUnder-sinkAquasana Claryum 3-Stage Max Flow Under-Sink Filter (AQ-6300M)AquasanaTreatsleadPrice$$Certified for Lead (NSF/ANSI 53, WQA)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price at Aquasana
Also goodCountertopAquasana Clean Water Machine Countertop Filter (AQ-CWM2)AquasanaTreatsleadPrice$$Certified for Lead (NSF/ANSI 53, WQA)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price at Aquasana
See all 16 drinking-water options for lead
More drinking-water options for lead
PickProductDetails and priceCertificationWhy it’s listedLink
Also goodReverse osmosisSmartFlow® Reverse OsmosisAquasana · Treats only drinking water at its own faucet, not showers or the rest of the house.TreatsleadTechnologyReverse osmosisPrice$$$Certified for lead (WQA)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price at Aquasana
Also goodUnder-sinkWaterdrop G3P600 Tankless Reverse-Osmosis SystemWaterdropTreatsleadPrice$$$Certified for Lead (NSF/ANSI 58-2024, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price at Waterdrop
Also goodUnder-sinkWaterdrop G3P800 Tankless Reverse-Osmosis SystemWaterdropTreatsleadPrice$$$Certified for Lead (NSF/ANSI 58-2024, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price at Waterdrop
Also goodCountertopAquaTru Carafe Countertop Reverse-Osmosis Purifier (AT100)AquaTruTreatsleadPrice$$$Certified for Lead (NSF/ANSI 58, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodCountertopAquaTru Classic Countertop Reverse-Osmosis Purifier (AT2000)AquaTruTreatsleadPrice$$$Certified for Lead (NSF/ANSI 58, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodUnder-sinkAquasana Claryum 2-Stage Under-Sink Filter (AQ-5200)AquasanaTreatsleadPrice$$Certified for Lead (NSF/ANSI 53, WQA)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodPitcherCulligan ZeroWater 10-Cup Pitcher (ZEROP10)Culligan ZeroWaterTreatsleadPrice$Certified for Lead (NSF/ANSI 53, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodUnder-sinkFrizzlife SP99 Under-Sink FilterFrizzlife Technology IncTreatsleadPrice$$Certified for Lead (NSF/ANSI 53-2024, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodFaucet-mountPUR Plus Faucet Filter (FM2500V)PURTreatsleadPrice$Certified for Lead (NSF/ANSI 53, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodCountertopPatriot Pure Ultimate Water Filtration SystemPatriot Pure (4Patriots)TreatsleadPrice$$Certified for Lead (NSF/ANSI 53, NSF, IAPMO)Why it’s listed: its current certification names lead, found in Chicago’s record.See the evidenceCheck price on Amazon
Also goodReverse osmosisiSpring RCC7AK Alkaline Reverse Osmosis SystemiSpring · It treats only the water from its own faucet and sends part of the water to the drain; the NSF listing for the plain RCC7AK covers dissolved solids, not lead or PFAS.Use code REFISPRING at checkout: 10% off your first iSpring order.TechnologyReverse osmosisPrice$$Brand lab-tested, not independently certified for leadSee the evidenceCheck price at iSpring
Also goodReverse osmosisiSpring RO5004F Tankless Reverse Osmosis System with UViSpring · Its PFAS and lead reduction claims are iSpring's own, with no third-party certification named for this model, and it treats only the water at its own faucet.Use code REFISPRING at checkout: 10% off your first iSpring order.TechnologyReverse osmosisPrice$$$Brand lab-tested, not independently certified for leadSee the evidenceCheck price at iSpring
Also goodReverse osmosisWaterdrop X12 Reverse Osmosis SystemWaterdrop · Its IAPMO NSF/ANSI 58 certification covers TDS reduction only, so its PFAS and lead claims rest on Waterdrop's own SGS lab testing.TechnologyReverse osmosisPrice$$$$Brand lab-tested, not independently certified for leadSee the evidenceCheck price at Waterdrop

★ Best available: iSpring WGB32B-PFKS PFAS & Heavy Metals Whole House Filter, the best fit here; nothing in this group is certified yet.

Filters for the lead found in Chicago water
PickProductDetails and priceCertificationWhy it’s listedLink
★ Best availableWhole-houseiSpring WGB32B-PFKS PFAS & Heavy Metals Whole House FilteriSpring · It does not reduce total dissolved solids or soften hard water, and its PFAS result comes from SGS lab testing rather than an NSF/ANSI certification.Use code REFISPRING at checkout: 10% off your first iSpring order.Price$$$Brand lab-tested, not independently certified for leadSee the evidenceCheck price at iSpring

Also: hard water picks →

PurityMap earns a commission from these links. "Best choice" and "Budget pick" go to certified products first; commission never decides them. As an Amazon Associate, PurityMap earns from qualifying purchases. Affiliate disclosure.

Lead service lines

Ask your utility first

Chicago Department of Water Management reported 350,531 lead and 10,326 galvanized service lines to replace in EPA’s inventory (2026Q2). Many utilities replace these lines for free or share the cost. Ask Chicago Department of Water Management whether your home’s line is on its list before you pay anyone.

Local help

Think your plumbing may be adding lead?

Call to be connected with a local plumbing provider about lead service lines, repiping or fixture replacement.

Is this right for my home?

Choose your situation

Your situation
Your path: I live in an older buildingLead from plumbing is the main question

Older buildings may have lead service lines, solder or fixtures. Chicago’s record shows lead at 6.4 µg/L (15 µg/L federal action level). Test first-draw water, then filter if needed.

Look forLead reduction: NSF/ANSI 53 (lead)
How to test your tap →
Your path: I care about PFASCheck what was tested

None of the 29 PFAS tested was detected in Chicago’s record. If PFAS matters to you, a filter certification names each compound it covers.

Look forNSF/ANSI 53 or 58, with each compound you care about named on the listing
PFAS in Chicago →
Your path: My water tastes of chlorineChicago’s system disinfects with chlorine

Utilities keep a disinfectant in the pipes on the way to your tap. A carbon filter certified for chlorine reduces the taste.

Look forNSF/ANSI 42 (chlorine taste and odor)
Water treatment technologies →
Your path: I have scale or hard waterChicago water is hard (8.2 gpg)

Scale is a comfort and appliance issue, not a health one.

Look forSoftener: NSF/ANSI 44 (softeners)
Hard water in Chicago →
Your path: I want the broadest reductionReverse osmosis at one tap

Reverse osmosis reduces many dissolved contaminants, including lead and minerals, at a single faucet, with some water sent to drain.

Look forNSF/ANSI 58
Compare treatments →
Questions

Chicago tap water FAQ

Follow Chicago’s water

Get one email when Chicago’s record changes.

Follow Chicago’s water →
Is Chicago tap water safe to drink?

PurityMap does not give a safe/unsafe verdict; it shows what the public records measured. For Chicago, no regulated PFAS were detected in EPA's 2024 testing; the lead 90th-percentile result was 6.4 µg/L against the 15 µg/L action level. CHICAGO (PWSID IL0316000) has a Purity Score of 91/100 (confidence: high), assessed at the water-system level and computed only from contaminants that were measured. Water can change in your own pipes, so a certified test is the only way to know what comes out of your tap. What we found →

Who provides tap water in Chicago?

CHICAGO (PWS ID IL0316000) is the public water system on record for Chicago, Illinois, serving about 2,721,308 people. Confirm the utility on your water bill before acting on a specific finding. Water utility →

Where does Chicago get its drinking water?

Surface water (primary source of record in EPA SDWIS). Water utility →

Are PFAS "forever chemicals" in Chicago's water?

None of the 29 PFAS in EPA's UCMR 5 testing (2024-01-08 to 2024-10-08) was detected. "Not detected" means below the lab's reporting limit, not proven zero. What we found →

Is there lead in Chicago's tap water?

CHICAGO's most recent lead 90th-percentile result (2026) was 6.4 µg/L, below the 15 µg/L action level. That figure comes from sampled homes; lead usually enters from a building's own pipes and fixtures, so only a test at your tap tells you what you drink. Your household →

What does the latest Chicago water report show?

PurityMap's current record for Chicago holds 34 findings: 1 above a reference, 3 detected within the reference and 30 not detected. Each finding links to its dated public record; a parameter that was never monitored is shown as pending, not as a pass. Records →

Is Chicago's water hard?

Chicago's water is recorded as 8.2 gpg, hard. Hardness is an aesthetic and plumbing characteristic, not a health-based limit. Choose your situation →

Data and sources

34 records, each traceable

  • EPA UCMR 5
  • EPA SDWIS (Lead & Copper Rule)
  • Utility CCR
ContaminantMeasuredReferenceSampledSource
Water hardness8.2 gpgAesthetic, no federal health limit2025Utility CCR ↗ (opens in a new tab)
Lead (90th percentile)6.4 µg/L15 µg/L federal action level2026EPA SDWIS (Lead & Copper Rule) ↗ (opens in a new tab)
Total trihalomethanes (TTHM)26.4 ppb80 ppb federal MCL2025Utility CCR ↗ (opens in a new tab)
Haloacetic acids (HAA5)13.8 ppb60 ppb federal MCL2025Utility CCR ↗ (opens in a new tab)
11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)< 5 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)< 5 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)< 5 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)< 2 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)< 5 ng/L (not detected)10 ng/L federal MCL (2024)2024EPA UCMR 5 ↗ (opens in a new tab)
Lithium< 9 µg/L (not detected)10 µg/L EPA health reference level (screening, not a legal limit)2024EPA UCMR 5 ↗ (opens in a new tab)
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)< 5 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)< 6 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)< 20 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoro-3-methoxypropanoic acid (PFMPA)< 4 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoro-4-methoxybutanoic acid (PFMBA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorobutanesulfonic acid (PFBS)< 3 ng/L (not detected)2,000 ng/L EPA health advisory (screening, not a legal limit)2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorobutanoic acid (PFBA)< 5 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorodecanoic acid (PFDA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorododecanoic acid (PFDoA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoroheptanesulfonic acid (PFHpS)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoroheptanoic acid (PFHpA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorohexanesulfonic acid (PFHxS)< 3 ng/L (not detected)10 ng/L federal MCL (2024)2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorohexanoic acid (PFHxA)< 3 ng/L (not detected)400,000 ng/L Michigan EGLE state MCL (strictest US state)2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorononanoic acid (PFNA)< 4 ng/L (not detected)10 ng/L federal MCL (2024)2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorooctanesulfonic acid (PFOS)< 4 ng/L (not detected)4.0 ng/L federal MCL (2024)2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorooctanoic acid (PFOA)< 4 ng/L (not detected)4.0 ng/L federal MCL (2024)2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoropentanesulfonic acid (PFPeS)< 4 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoropentanoic acid (PFPeA)< 3 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorotetradecanoic acid (PFTA)< 8 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluorotridecanoic acid (PFTrDA)< 7 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
Perfluoroundecanoic acid (PFUnA)< 2 ng/L (not detected)No federal or state limit; shown for transparency2024EPA UCMR 5 ↗ (opens in a new tab)
  • UCMR5 Analytical Results

    UCMR5 Analytical Results: CHICAGO (IL0316000)

    US EPA

    Published
    2026-10-15
    Newest sample
    2024-10-08
    Findings here
    30
  • State SDWIS Compliance Record

    Lead & Copper Rule 90th-percentile: CHICAGO (IL0316000)

    US EPA SDWIS

    Published
    2026-10-13
    Newest sample
    2026
    Findings here
    1
  • Consumer Confidence Report (CCR)

    City of Chicago Dept. of Water Management 2025 Consumer Confidence Report (CCR)

    City of Chicago Dept. of Water Management

    Published
    2025-01-01
    Newest sample
    2025
    Findings here
    3

Methodology: how we analyze water. Prepared with AI assistance and reviewed by the PurityMap Editorial Team before publication.

Methodology

How PurityMap reads Chicago’s water

  1. 01Source data

    EPA SDWIS, EPA UCMR 5 and utility reports, each dated and linked.

  2. 02Normalize

    Units converted to one basis; a non-detect kept distinct from zero.

  3. 03Classify

    Each result tagged by reference type: MCL, action level, screening level or aesthetic.

  4. 04Compare to the named reference

    Every value sits against its own reference, never a blended one.

  5. 05Score

    Measured subjects summarised at the water-system level; an open health-based violation caps the score.

  6. 06Match treatment

    Treatment is matched to what was found; a product is called certified only when its current certification names it.

What the Purity Score means: a summary of this water system’s published record, capped while a health-based violation is open. It is not a test of any tap. CHICAGO · PWSID IL0316000 · Purity Score 91/100 (Excellent) · Confidence: high · Assessed at the water-system level

Full methodology →

Something off with your water's smell, color or taste?

Start with the hot-or-cold tap check. Where Chicago Department of Water Management reported something related, it's shown below.

ZIP codes in Chicago

Show all 86 ZIP codesShow fewer

Look up water quality by ZIP code →